A method for preparing samples for analyzing irradiation damage behavior of Mg / Al laminated material interfaces

Abstract

The present invention discloses a method for preparing a sample for analyzing the interface damage behavior of Mg / Al laminated materials. The method comprises the following steps: using SRI M software to calculate the damage behavior of Mg / Al laminated materials at different energies. + The incidence depth in the Mg / Al stacked material is determined, and the depth of the irradiation damage layer of the incident ions with specific energy is calculated; according to the results of SRI M calculation, the ion beam cutting is performed on the ion irradiated sample; ion beams with different beam current sizes are sequentially selected to thin the cut interface sample; by adjusting parameters such as the electrolytic polishing liquid ratio, polishing temperature, polishing time, and polishing voltage, the optimal "rapid polishing" process parameters of the Mg / Al stacked material interface sample are explored; this method can effectively complete the preparation of Mg / Al interface transmission electron microscopy samples in Mg / Al stacked materials after ion irradiation by combining SRI M software simulation, ion beam micro-nanoscale processing, differentiated thinning process and "rapid polishing" treatment, so as to realize the analysis of Mg / Al interface radiation damage behavior and the rapid screening of high-performance Mg / Al stacked materials.

Description

Technical Field

[0001] The present invention relates to the study of nuclear fuel cycle and radiation effects. Background Art

[0002] Following the U.S. Department of Energy's "De-enrichment Program," UMo / Al fuel, due to its high uranium loading and excellent service performance, has become the mainstream development direction for research reactor fuel elements worldwide. However, as service temperatures rise and burnup increases, UMo / Al fuel still faces failure risks such as pillow deformation and blistering due to radiation swelling and reduced thermal conductivity, seriously affecting reactor operational safety.

[0003] To address this issue, researchers have attempted to replace Al with a magnesium (Mg) matrix that does not react with U or Mo, resulting in the formation of UMo / Mg / Al fuel, which is widely considered the most promising solution. Although multiple off-core research results have shown that UMo / Mg / Al fuel exhibits good mechanical and thermal properties, it is still unknown whether the UMo / Mg / Al fuel, especially the Mg / Al laminated material used as the fuel cladding, can still maintain good interfacial bonding, high-temperature strength, and radiation swelling resistance after being damaged by high-dose fast neutron irradiation, without significantly affecting its neutron economy and thermal conductivity. Therefore, screening a Mg / Al laminated cladding material with excellent comprehensive performance is a primary issue that needs to be addressed in this field.

[0004] Neutron irradiation can produce numerous irradiation defects in Mg / Al laminates, affecting their thermal and mechanical properties. Reactor neutron irradiation, characterized by high cost, long cycles, and numerous interfering factors (broad neutron energy spectrum and uneven temperature distribution), hinders the screening of Mg / Al laminates and the study of their irradiation damage behavior. Ion irradiation, due to its similar initial processes, such as atomic displacement, offers numerous advantages, including single, stable energy, controllable temperature, low experimental cost, short cycles, and virtually no radioactivity. Therefore, ion irradiation is widely used internationally to simulate neutron damage behavior in materials. However, ion irradiation is limited by electron energy loss, resulting in a relatively shallow irradiation depth, typically on the order of μm. Therefore, the preparation of transmission electron microscopy (TEM) samples of the Mg / Al interface in ion-irradiated Mg / Al laminates is crucial for analyzing Mg / Al interface damage behavior and for the rapid screening of high-performance Mg / Al laminates. However, there are currently no reports on sample preparation methods for analyzing irradiation damage behavior of the Mg / Al interface. In view of the above situation, it is necessary to propose an effective sample preparation method. Summary of the Invention

[0005] In order to solve the current problems, the purpose of the present invention is to provide a method for preparing samples for analyzing the radiation damage behavior of Mg / Al laminated materials, which is mainly used to effectively complete the preparation of transmission electron microscopy samples of the Mg / Al interface in the Mg / Al laminated materials after ion irradiation, so as to realize the analysis of the radiation damage behavior of the Mg / Al interface and the rapid screening of high-performance Mg / Al laminated materials.

[0006] In order to achieve the above technical objectives, the technical solutions adopted by the present invention are as follows.

[0007] A method for preparing samples for analyzing the radiation damage behavior of Mg / Al laminated material interfaces is provided. The method combines software simulation, ion beam micro-nanoscale processing, differentiated thinning, and "speed polishing" processing to achieve the preparation of samples for analyzing the radiation damage behavior of Mg / Al laminated material interfaces after ion irradiation. The method includes the following steps:

[0008] Step 1: SRIM calculation: SRIM simulation software is used to calculate the penetration depth of incident ions of different energies in the Mg / Al stacked material, and the depth of the irradiation damage layer of incident ions of a specific energy is calculated;

[0009] Step 2: Ion beam cutting: Based on the results of SRIM calculation, electron beam and ion beam deposition are performed perpendicular to the Mg / Al interface using a focused ion beam scanning electron microscope (FIB), and ion beam cutting is performed along the irradiation depth direction. The cutting depth is approximately 2 to 3 times the SRIM calculation result.

[0010] Step 3, ion beam thinning: Sequentially select ion beams of different beam currents to thin the cut interface sample. Due to the different hardnesses of Al alloy and Mg alloy, the thinning time of the Al alloy area needs to be extended or the ion beam current needs to be increased during the thinning process until the electron beam can easily penetrate the area to be observed near the interface, the interface remains intact, and the sample does not undergo obvious deformation;

[0011] Step 4. Exploration of the "rapid polishing" process for unirradiated samples: Cut and thin the unirradiated Mg / Al laminate interface sample with reference to the ion beam cutting and thinning processes in steps 2 and 3, and perform "rapid polishing" on the unirradiated Mg / Al laminate interface sample after recrystallization annealing using an electrolytic polishing and etching device. The "rapid polishing" process parameters for the Mg / Al laminate interface sample are explored, with the elimination of the ion damage layer introduced by the FIB Ga ion beam as the standard.

[0012] Step 5: Rapid polishing of ion irradiated samples: The sample interface of the non-irradiated Mg / Al stack material after recrystallization annealing is subjected to a rapid polishing process. The sample after ion beam thinning is subjected to a rapid polishing process to eliminate the ion damage layer introduced by the Ga ion beam during the thinning process.

[0013] Step 6: TEM characterization: After the "speed casting" is completed, the bright field and dark field images of the sample are observed using a transmission electron microscope. If irradiation defects can be observed and there are no obvious ion beam processing streaks and deformations in the sample, the sample preparation is completed.

[0014] The technical solution provided by the present invention is further optimized, and the melting point (T m ) The highest temperature is about 660℃, and the recrystallization temperature is about 0.4T m , that is, the recrystallization annealing temperature is 264°C;

[0015] Further optimization of the above technical solution, the "speed polishing" treatment of the Mg / Al laminated material interface sample refers to the use of electrolytic polishing principle to quickly polish the TEM sample prepared by FIB. Unlike conventional electrolytic polishing, the sample polished by electron microscope is usually The polishing time for FIB-prepared TEM samples ranges from tens of seconds to hundreds of seconds. However, the TEM samples prepared by FIB are only about 10μm×20μm. Too high a polishing efficiency or too long a polishing time will easily damage the sample. Therefore, the polishing voltage of the "speed polishing" process is only 10V, and the polishing time is only a few tenths of a second.

[0016] The polishing liquid used for "speed polishing" treatment is 8% to 10% perchloric acid + 90% to 92% alcohol solution, the "speed polishing" voltage is between 10V and 12V, the "speed polishing" temperature is between -40℃ and -35℃, and the "speed polishing" time is between 0.05s and 0.3s.

[0017] Further optimization and improvement, the incident ion is Mg + For ions, the energy range calculated by SRIM software is 10keV~10MeV.

[0018] Further optimization and improvement: the specific energy is 1.5 MeV, the depth of the irradiation damage layer is between 1500 nm and 3000 nm, and the peak depth is about 2250 nm.

[0019] Further optimization and improvement are made, the ion beam cutting depth is 8 μm to 10 μm, and the width is 15 μm to 20 μm.

[0020] Further optimization and improvement are made, the ion beam parameters of different beam current sizes are between 5kV and 30kV, 44pA and 0.44nA, the single-side single thinning time is 10s to 2min, and the beam current size and thinning time are adjusted according to the actual situation of sample thinning.

[0021] Compared with the prior art, the technical effect achieved by the present invention is that: a method for preparing samples for analyzing the irradiation damage behavior of the interface of Mg / Al laminated materials is provided. By combining SRIM software simulation, ion beam micro-nanoscale processing, differentiated thinning process and "rapid polishing" treatment, the preparation of transmission electron microscopy samples of the Mg / Al interface in the Mg / Al laminated material after ion irradiation can be effectively completed, so as to realize the analysis of the irradiation damage behavior of the Mg / Al interface and the rapid screening of high-performance Mg / Al laminated materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 1.5MeV Mg + SRIM simulation results of ion-irradiated Mg alloy.

[0023] Figure 2 Schematic diagram of ion beam cutting perpendicular to the Mg / Al interface using FIB. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] like Figure 1 、 Figure 2 As shown, a method for preparing a sample for analyzing the radiation damage behavior of a Mg / Al laminated material interface comprises the following steps:

[0026] Step 1: Use the "Ion Distribution and Quick Calculation of Damage" function of the Stopping and Range of Ions into Matter (SRIM) software to calculate the Mg + The incident depth at the interface of Mg / Al stacked materials, combined with Mg + The beam yield was calculated by selecting an appropriate injection energy (1.5 MeV) to obtain the data on the distribution of irradiated defect (vacancy) concentration with depth. Then, the calculation formula between the dislocation damage rate (dpa) and the irradiated defect concentration was used to construct the Mg ion density under the injection energy of 1.5 MeV. + The relationship curve between ion beam irradiation damage (dpa)-irradiation depth-ion concentration is obtained, and the Mg content is calculated under the injection energy of 1.5MeV. + Depth of the irradiation damaged layer at the interface of Mg / Al stacked materials;

[0027] Step 2: Align the irradiated surface of the Mg / Al interface sample with the Ga ion beam of the FIB, select a certain area perpendicular to the Mg / Al interface and perform electron beam and ion beam deposition in sequence to avoid damage to the sample in the area during ion beam cutting, and perform ion beam cutting along the direction of ion beam irradiation. The cutting method is to dig "V" grooves on both sides and then "U" cut. In addition, according to the results of SRIM calculation, 1.5MeVMg + The peak depth of the irradiation damage layer at the interface of the Mg / Al stacked material is about 2250nm. In order to reduce the impact of the ion beam cutting process on the irradiation damage layer, the cutting depth is controlled between 8μm and 10μm.

[0028] Step 3: Use the nanomanipulator that comes with the FIB to extract the "U"-cut sample and weld it to a half-loaded copper mesh. Then, select parameters such as 30kV@0.44nA, 30kV@90pA, 5kV@63pA, and 5kV@44pA to thin the interface sample after cutting. During the thinning process, the front and back sides of the sample should be thinned alternately. Moreover, since the hardness of Al alloy is greater than that of Mg alloy, when thinning on the same side, the thinning time close to the Al alloy side should be longer or the beam current should be larger to ensure that the substrates on both sides of the Mg / Al interface can be thinned to similar thicknesses at the same time. At the same time, in order to avoid uneven thickness on both sides of the interface causing curling and deformation of the sample, the thinning area must be gradually reduced and the interface and both sides of the interface must be thinned alternately until the electron beam can easily penetrate the area to be observed near the interface, the interface remains intact, and the sample does not undergo obvious deformation.

[0029] Step 4: Cut and thin the unirradiated Mg / Al laminate interface sample by referring to the ion beam cutting and thinning processes in steps 2 and 3, prepare the electrolyte required for the "speed polishing" treatment, and connect the electrodes, power supply, timer of the electrolytic polishing and etching device and the unirradiated Mg / Al laminate interface sample after recrystallization annealing. By adjusting the parameters such as the electrolytic polishing solution ratio, polishing temperature, polishing time, and polishing voltage, the optimal "speed polishing" process parameters for the Mg / Al laminate interface sample are explored;

[0030] Step 5: After ion cutting and thinning of the Mg / Al stacked material interface sample after ion irradiation, it is connected to the electrodes, timer and power supply of the electrolytic polishing and etching device, and subjected to "speed polishing" treatment using the optimal "speed polishing" process parameters explored in advance to eliminate the ion damage layer introduced by the Ga ion beam during the thinning process;

[0031] Step 6: Place the sample after "speed-throwing" treatment into the transmission electron microscope, draw the vacuum, adjust the acceleration voltage of the transmission electron microscope, the size of the electron beam spot, the area of ​​the sample and the crystal axis, observe the bright and dark field images of the sample, confirm that there are no obvious traces of ion beam processing in the sample, no obvious deformation, and the morphology of the irradiation defects can be clearly observed, then the sample preparation is completed.

[0032] The above is a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the principles and core ideas of the present invention. These modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a sample for analyzing irradiation damage behavior of a Mg / Al laminated material interface, comprising the following steps: Step 1: SRIM calculation: SRIM simulation software is used to calculate the penetration depth of incident ions of different energies in the Mg / Al stacked material, and the depth of the irradiation damage layer of incident ions of a specific energy is calculated; Step 2: Ion beam cutting: Based on the results of SRIM calculation, a focused ion beam scanning electron microscope (FIB) is used to deposit electron beams and ion beams perpendicular to the Mg / Al interface, and ion beam cutting is performed along the irradiation depth direction. The cutting depth is 2 to 3 times the SRIM calculation result. Step 3, ion beam thinning: Sequentially select ion beams of different beam currents to thin the cut interface sample. Due to the different hardnesses of Al alloy and Mg alloy, the thinning time of the Al alloy area needs to be extended or the ion beam current needs to be increased during the thinning process until the electron beam can easily penetrate the area to be observed near the interface, the interface remains intact, and the sample does not undergo obvious deformation; Step 4: Rapid polishing of unirradiated samples: Cut and thin the unirradiated Mg / Al laminate interface sample according to the ion beam cutting and thinning processes in steps 2 and 3, and perform rapid polishing on the unirradiated Mg / Al laminate interface sample after recrystallization annealing using an electrolytic polishing and etching device. The ion damage layer introduced by the Ga ion beam from the FIB is eliminated as a standard, and the rapid polishing process parameters of the Mg / Al laminate interface sample are obtained. Step 5: Rapid polishing of ion-irradiated samples: Using the same process parameters as for the interface sample of the unirradiated Mg / Al stack material after recrystallization annealing, the sample after ion beam thinning is subjected to rapid polishing to eliminate the ion damage layer introduced by the Ga ion beam during the thinning process. Step 6. TEM characterization: After the "speed casting" is completed, the bright field and dark field images of the sample are observed using a transmission electron microscope. If irradiation defects can be observed and there are no obvious ion beam processing streaks and deformations in the sample, the sample preparation is complete.

2. A method for preparing a sample for analyzing irradiation damage behavior of a Mg / Al laminated material interface according to claim 1, characterized in that: Melting point T of Mg / Al alloy m The highest temperature is 660℃, and the recrystallization temperature is 0.4T m , that is, the recrystallization annealing temperature is 264°C.

3. A method for preparing a sample for analyzing irradiation damage behavior of a Mg / Al laminated material interface according to claim 1, characterized in that: The polishing liquid used for "speed polishing" treatment is 8% to 10% perchloric acid + 90% to 92% alcohol solution.

4. A method for preparing a sample for analyzing irradiation damage behavior of a Mg / Al laminated material interface according to claim 3, characterized in that: The "quick throw" voltage is between 10V and 12V, and the "quick throw" temperature is between -40℃ and -35℃.

5. A method for preparing a sample for analyzing irradiation damage behavior of a Mg / Al laminated material interface according to claim 4, characterized in that: The "quick throw" time is between 0.05s and 0.3s.

6. A method for preparing a sample for analyzing irradiation damage behavior of a Mg / Al laminated material interface according to claim 1, characterized in that: The incident ion is Mg + For ions, the energy range calculated by SRIM software is 10keV~10MeV.

7. A method for preparing a sample for analyzing irradiation damage behavior of a Mg / Al laminated material interface according to claim 1, characterized in that: The specific energy is 1.5 MeV, the depth of the irradiated damaged layer is between 1500 nm and 3000 nm, and the peak depth is 2250 nm.

8. A method for preparing a sample for analyzing irradiation damage behavior of a Mg / Al laminated material interface according to claim 1, characterized in that: The ion beam cutting depth is 8 μm to 10 μm, and the width is 15 μm to 20 μm.

9. A method for preparing a sample for analyzing irradiation damage behavior of a Mg / Al laminated material interface according to claim 1, characterized in that: The ion beam parameters of the different beam current sizes are between 5kV and 30kV, 44pA and 0.44nA, and the single-side thinning time is 10s to 2min. The beam current size and thinning time are adjusted according to the actual thinning conditions of the sample.

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